Clutch for transmission power and method of manufacturing friction substance for the clutch

ABSTRACT

The present invention relates to a clutch for transmission power. The clutch for transmission power according to the present invention includes flywheel, clutch cover and clutch disk assembly positioning between the flywheel and the clutch cover; moreover, the clutch disk assembly includes a clutch facing having main body portion formed with a center hole in the middle thereof, and a contacting portion wherein one side thereof faces the friction pad at said flywheel side and the other side thereof faces the press plate of said clutch cover, and the portion facing each other between the friction pad and the press plate is made of carbon-carbon composition; a spline hub being overlapped with one side of the clutch facing wherein a spline groove is formed in the inner diameter thereof; and a connecting means for connecting the clutch facing with the spline hub. Furthermore, the clutch disk assembly and the method of manufacturing the friction substance for clutch according to the invention can improve assemblability and reduce weight by simplifying it as a single part without using shock absorbing apparatus such as coil spring or the like on clutch disk assembly. In addition, the power transmission of an engine can be improved, and also it has an effect that an automobile can start softly and slippery does not occur even at abrupt acceleration by providing with carbon-carbon composition or carbon-silicon carbide composition having excellent shock absorption function.

CROSS REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 120, this application is a divisionalapplication of U.S. application Ser. No. 10/825,070, filed Apr. 15,2004.

FIELD OF INVENTION

The present invention relates to a clutch for transmission power and amethod of manufacturing friction substance for the clutch, moreparticularly, to a clutch for transmission power and a method ofmanufacturing friction substance for the clutch wherein transmissionpower is excellent and soft start is attainable by simplifying thestructure of spline hub as a single part, as well as by applyingcarbon-carbon composition having high performance in durability, shockabsorption and friction.

BACKGROUND OF THE INVENTION

In general, a clutch characteristically requires responsecharacteristics, such as soft gearshift and fast and high transmissionpower, as a mechanical element for transmitting power wherein a drivingshaft and a driven shaft are connected to each other in mechanicaldevices. This clutch can be used for various industrial areas such asautomobiles, motorcycles, industrial machines, presses, ships, etc.

In particular, the clutch used for automobile is designed to allowslippery movement by half clutch operation to attain soft start forvehicles. Accordingly, high-temperature frictional heat can be createdwithin the range of 200° C.˜600° C. with this half clutch operation.

As a result, the clutch undergoes phenomena such as thermal load andfatigue, dynamic load by intermittent contact torque of the clutchcaused by friction, and deterioration of clutch cover and disk at hightemperature due to friction over the areas such as flywheel, clutchdisk, press plate, etc. since high torque power is transmitted byfriction.

Caused by this phenomena, fatigue, crack or the like are created bythermal load and dynamic load, and also fading is created due to thereduced friction coefficient at high temperature as well as at high RPM(revolutions per minute). This is the main cause for reducing the lifeof a clutch.

Various studies for solving the above-mentioned problem have beenprogressed until now. As for known solutions for these problems, thereare a clutch cushion plate, a rubber damper, wave spring, etc. which areused for the shock absorption structure, and also a method of providingventilation grooves at clutch disk or providing holes at flywheel orpress plate was developed as cooling system.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a clutch for transmissionpower for minimizing the damage on its life span which is induced by thefriction at high temperature by providing the material of clutch facingwith carbon-carbon composition having a simple structure without using acushion plate, a rubber damper, wave spring or cooling system.

It is another object of the invention to provide a method ofmanufacturing friction substance for the clutch wherein the frictionsubstance that is used for the clutch such as clutch facing, press padand friction pad can be produced with carbon-carbon composition.

A clutch for transmission power to achieve the first object of theinvention includes a flywheel, a clutch cover and a clutch disk assemblypositioning between the flywheel and the clutch cover, wherein theclutch disk assembly includes a clutch facing having the body portionformed with a center hole in the middle thereof, and a contactingportion wherein one side thereof faces the friction pad at the flywheelside and the other side thereof faces the press plate of the clutchcover, and the portion facing each other between the friction pad andthe press plate is made of carbon-carbon composition; a spline hub beingoverlapped with one side of the clutch facing wherein a spline groove isformed in the inner diameter thereof; and a combining means forcombining the clutch facing with the spline hub.

Moreover, the spline hub is formed with a boss for inserting into thecenter hole of the clutch facing, and the combining means includes aretainer ring being overlapped with the other side of the clutch facing;and a fastening member by passing through the clutch facing, the splinehub and the retainer ring. Here, the fastening member includes eitherbolt or rivet selectively.

On the other hand, the contacting portion is formed with carbon-carboncomposition which is composed of 20˜75 weight % of carbon fiber and25˜80 weight % of pitch.

Another aspect of the invention is that the contacting portion is madeof carbon-silicon carbide which is composed of 3˜20 weight % of silicon,10˜60 weight % of silicon carbide, and 20˜87 weight % ofpitch-containing carbon.

Furthermore, the carbon fiber is a single fiber, or it is formed bycontinuously woven carbon fabrics.

In another aspect of the invention, moreover, the body portion isintegrally formed with the contacting portion by using the samecarbon-carbon composition material which is used for the contactingportion.

Still another aspect of the invention is that the press plate isprovided with the press pad adjoining the clutch facing, and the presspad and the friction pad are formed with the same carbon-carboncomposition which is used for the contacting portion.

The method of manufacturing the friction substance for the clutch toachieve the second object of the invention can be divided into twosteps. The first step is to produce a two-dimensional preform, and thesecond step is to produce a three-dimensional preform.

The method of producing a two-dimensional preform includes the steps ofperforming a first thermal treatment wherein carbon fiber is thermallytreated for graphitization at a first thermal processing temperature,producing a prepreg wherein resin is sprayed on carbon fiber fabrics toform the prepreg, producing a preform wherein carbon fiber and resin arestacked on the prepreg to form the preform, producing a mold wherein themold is formed by using a press on the preform, and performing a secondthermal treatment wherein the mold is thermally treated at a secondthermal processing temperature.

Another aspect of the invention further includes the step of cutting thethermally treated carbon fiber at the length of 200˜2,000 μm by usingfiber-cutting machine between the first thermal treatment process andthe prepreg producing process.

Still another aspect of the invention includes a densification processfor densifying the mold at a predetermined density using acarbonization/impregnation process for pressurizing at the carbonizingpressure of 50˜2,000 kg/cm² within the range of 750˜1,400° C. for 3˜5hours between the mold producing process and the second thermaltreatment process. Here, the predetermined density is 1.3˜1.6 g/cm³.

In still further aspect of the invention, the first thermal processingtemperature is 2,000˜3,000° C. during the first thermal treatmentprocess.

In the step of producing a mold, moreover, the mold is composed of 20˜75weight % of carbon fiber and 25˜80 weight % of the resin, and molded byheating within the range of 200˜300° C. at the press.

In another aspect of the invention, the second thermal treatment processis performed at the maximum temperature for 35 hours under secondthermal processing temperature of 1,700˜2,500° C., vacuum level of 3˜5mmHg, and heat rising rate of 20˜100° C./hr.

In still another aspect of the invention, it further includes the stepsof performing a silicon powder addition process by adding silicon powderto the mold after the second thermal treatment process, and performing avacuum heating process for increasing the temperature within the rangeof 1,450° C.˜2,200° C. and maintaining it for 0.1˜5.0 hours under thevacuum atmosphere, and silicon powder 0.2˜5.0 times heavier than themold in weight ratio is added during the silicon powder additionprocess. After finishing the vacuum heating process, the mold iscomposed of 3˜25 weight % of silicon, 10˜65 weight % of silicon carbide,and 10˜80 weight % of carbon.

The method of producing a three-dimensional preform includes the stepsof heating for creating a thermal gradient between the inside andoutside of the preform by mounting a heating element on thethree-dimensional preform, infiltrating reaction gas containing 1˜6carbons per molecule inside the reactor, producing a mold by performingreaction under a predetermined condition, and performing a thermaltreatment on the mold.

Furthermore, the predetermined condition is heat rising rate of 10˜20°C./min, reaction temperature of 700˜1200° C., reaction gas concentrationof 10˜100%, and reaction pressure of 250˜1,500 mbar, and the thermaltreatment process is performed at the maximum temperature for 3˜5 hoursunder second thermal processing temperature of 1,700˜2,500° C., vacuumlevel of 3˜5 mmHg, and heat rising rate of 20˜100° C./hr.

Moreover, the friction substance produced by the above-mentioned twomethods can be used for any one or all of the clutch facing, frictionpad, and press pad on which friction is made in the clutch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a disassembled disk assembly of theclutch for transmission power according to the present invention.

FIG. 2 is a cross sectional view showing an assembled disk assembly ofthe clutch for transmission power of FIG. 1.

FIG. 3 is a cross sectional view showing a half of the clutch fortransmission power which is installed with a disk assembly according tothe present invention.

FIG. 4 is a flowchart showing a method of producing the frictionsubstance for the clutch in a two-dimensional preform according to thepresent invention.

FIG. 5 is a flowchart showing a method of producing the frictionsubstance for the clutch in a three-dimensional preform according to thepresent invention.

FIG. 6 is a horsepower-torque graph of the clutch wherein a conventionalorganic facing is provided with.

FIG. 7 is a horsepower-torque graph of the clutch wherein a conventionalcopper-ceramic facing is provided with.

FIG. 8 is a horsepower-torque graph of the clutch wherein acarbon-carbon composition facing according to the present invention isprovided with.

FIG. 9 is a graph showing the response characteristic of gear shift forthe clutch installed with a clutch disk assembly according to thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The clutch for transmission power according to the present inventionincludes a simplified spline hub and a clutch facing made ofcarbon-carbon composition having high performance in shock absorptioncapability. It can be simplified as a single part by the structure of aspline hub for improving assemblability and reducing weight, therebyimproving transmission power efficiency of engine.

Moreover, the clutch facing made of carbon-carbon composition replacesthe function of shock absorption, which was conventionally undertaken bycoil spring or the like that was installed in a spline hub so that softstart can be attainable for automobiles. Furthermore, since fading isnot generated due to its excellent properties of friction, abrasion andthermal shock resistance at high temperature, sufficient power can betransmitted, thereby enhancing its marketability and durability.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the attached drawings.

The clutch disk assembly according to the present invention includes aclutch facing 10 made of carbon-carbon composition wherein a center hole11 is formed in the middle thereof and a plurality of the firstfastening holes along the outer circumference of the center hole 11 areformed as shown in FIG. 1 and FIG. 2.

The clutch facing 10 can be divided into a body portion 10 a and acontacting portion 10 b being integrated. The body portion 10 a is aportion to be combined with a spline hub 20 to be described later, andthe contacting portion 10 b is a portion to be contacted with a frictionpad 71 and a press pad 61 to be described later. Accordingly, bodyportion 10 a and contacting portion 10 b can be separately produced forcombination and use, if required.

Furthermore, it has a spline hub 20 wherein a boss 22 being overlappedwith one side of the clutch facing 10 and inserted into the center hole11 is formed on one side, and a plurality of the second fastening holes23 being communicated with a plurality of the first fastening holes 12are formed along the circumference. Moreover, a plurality of splinegrooves 21 are formed in the vertical direction of the spline hub on theinner diameter of a bore which is formed in the middle of the spline hub20.

Furthermore, a retainer ring 30 being overlapped with the firstfastening holes 12 is formed on the other side of the clutch facing 10.A plurality of the third fastening holes 31 being communicated with thefirst fastening holes 12 are formed on this retainer ring 30.

Therefore, first fastening holes 12, second fastening holes 23 and thirdfastening holes 31 are communicated with one another for combiningclutch facing 10, spline hub 20 and retainer ring 30 at the same time bya combining means. This combining means comprises a plurality of bolts40 as shown in the drawing, and other types of combining means such asrivet or the like can be used if required. Each of fastening holes 12,23 and 31 is formed with 10˜20 in number.

On the other hand, the clutch facing 10 made of carbon composition isformed with carbon-carbon composition which is composed of 20˜75 weight% of carbon fiber and 25˜80 weight % of pitch, or with carbon-siliconcarbide composition which is composed of 3˜20 weight % of silicon, 10˜60weight % of silicon carbide, and 20˜87 weight % of pitch-containingcarbon. Moreover, the carbon fiber is formed with a single fiber or bystacking continuously woven carbon fabrics.

The clutch disk assembly according to the present invention is installedwithin clutch cover 50 as shown in FIG. 3. Furthermore, press plate 60provided with press pad 61 is positioned on the right of the clutchfacing 10 which is installed within clutch cover 50, and flywheel 70provided with a friction pad 71 is positioned on the left.

Also, press pad 61 and friction pad 71 can be made of carboncomposition. For installing friction pad 71 made of carbon composition,a groove 72 at the depth of 5˜8 mm is formed on the surface of flywheel70 on which each of them is provided, and adhesive agent is coated witha brush at the depth of 0.2˜0.6 mm on this groove 72, and then thecoated adhesive agent is dried within the range of 70˜80° C. for 20˜30minutes.

Then, friction pad 71 is installed on each groove 72 by pressurizingwith 350˜1,000 KN/m² and holding it for curing within the range of150˜230° C. for 15˜30 minutes, or it is fastened by bolts. Thisinstallation can also be used for press pad 61 made of carboncomposition. In the present embodiment, it is illustrated that press pad61 is attached to press plate 60 without providing a separate groove.

On the other hand, in another embodiment that is not shown in thedrawing, it can be provided by installing a cushion plate on the splinehub, and bonding a clutch facing made of carbon composition to thiscushion plate as used for conventional structure of a clutch disk. Atthis time, clutch facing is made of a master form or 3˜6 pads, and thecushion plate of spline hub is also formed with a master form or bydividing into 3˜6 pads in paddle type, and a clutch facing made ofcarbon composition is bonded with adhesive agent. Here, a separatecushion absorption structure is not required for the cushion plate asused for conventional clutches.

For a bonding method, moreover, bonding is performed by cleaning thecushion plate and clutch facing made of carbon composition with alcoholand drying at about 80° C. for 20 minutes, and then coating the cushionplate and carbon-carbon composition with adhesive agent at 0.20.6 mm wetthickness and drying within the range of 70˜80° C. for 20˜30 minutes,and then pressurizing at the press pressure of 350˜1,000 KN/m², heatingwithin the range of 150˜230° C. and holding it for 5˜30 minutes forcuring.

Hereinafter, an embodiment for a method of manufacturing the frictionsubstance for a clutch, which is used for a clutch facing, a frictionpad, a press pad in clutches, will be described.

For the method of manufacturing the friction substance for a clutchaccording to the present invention, PAN (polyacrylonitrile)-based carbonfiber is used. The friction substance can be manufactured by thefollowing processes, more particularly it can be manufactured bytwo-dimensional and three-dimensional forms.

First, as shown in FIG. 4, the method of manufacturing a two-dimensionalpreform includes the steps of performing a first thermal treatmentwherein carbon fiber is thermally treated for graphitization at a firstthermal processing temperature (S100) for improving thermalconductivity, producing a prepreg wherein resin is sprayed on carbonfiber fabric for forming the prepreg (S110), producing a preform whereincarbon fiber and resin are stacked on the prepreg to form the preform(S120), producing a mold wherein the mold is formed by using a press onthe preform (S130), and performing a second thermal treatment whereinthe mold is thermally treated at a second thermal processing temperature(S150).

Furthermore, carbon-silicon carbide composition can be manufactured byperforming a silicon powder addition process (S200) and a vacuum heatingprocess (S210) additionally after performing the above-mentionedprocesses. Such divided processes will be described separately as thesteps S1 and S2 in FIG. 4.

First, the first thermal treatment process S100 for manufacturingcarbon-carbon composition as the step S1 is a graphitization process toimprove the thermal conductivity of carbon fiber by performing a thermaltreatment at high temperature on PAN-based carbon fiber at first thermaltreatment temperature of 2,000˜3,000° C. Moreover, the carbon fiber isformed with a single fiber or by stacking continuously woven carbonfabrics, and a cutting process for cutting the thermally treated carbonfiber at the length of 200˜2,000 μm is performed using fiber cuttingmachine when carbon fiber is used for a single fiber.

In the prepreg producing process S110, a prepreg is produced byuniformly scattering resin such as pitch or resin which is crushed by acrusher at the fineness of 0.5˜10 μmon the carbon fiber, and heating itwithin the range of 180˜270° C.

In the preform producing process S120, a preform is produced byuniformly stacking the cut carbon fiber and the crushed resin on theprepreg.

In addition, a required mold is produced after heating the preformwithin the range of 200˜300° C. during the mold producing process S130,and a densification process S140 for densifying the mold can be addedseparately after the mold producing process S130. In the densificationprocess S140, a mold is densified at a predetermined density bypressurizing at the carbonizing pressure of 50˜2,000 kg/cm² within therange of 750˜1,400° C. for 35 hours, and performing acarbonization/impregnation process. Here, the predetermined densitythereof is 1.3˜1.6 g/cm³.

Next, the second thermal treatment process S150 is performed at themaximum temperature for 3˜5 hours under second thermal processingtemperature of 1,700˜2,500° C., vacuum level of 3˜5 mmHg, and heatrising rate of 20˜100° C./hr.

On the other hand, the step S2 for manufacturing carbon-silicon carbidecomposition by adding silicon powder to the surrounding of low densitycarbon-carbon composition which was produced using the above-mentionedmethod can be applied.

For this, silicon powder addition process S200 and vacuum heatingprocess S210 can be applied additionally. Silicon powder 0.2˜5.0 timesheavier than the mold in weight ratio is added to the surrounding of themold during silicon powder addition process S200, and carbon-siliconcarbide composition is produced by increasing the temperature within therange of 1,450° C.˜2,200° C. and maintaining it for 0.1˜5.0 hours underthe vacuum atmosphere during vacuum heating process S210.

The carbon-silicon carbide composition produced in this step is composedof 3˜25 weight % of silicon, 10˜65 weight % of silicon carbide, and10˜80 weight % of carbon.

Next, as shown in FIG. 5, the manufacturing method by using athree-dimensional preform includes the steps of heating for creatingthermal gradient between the inside and outside of the preform bymounting a heating element on the middle of the three-dimensionalpreform woven with carbon fiber (S300), infiltrating reaction gas, suchas methane, ethane, propane, butane, pentane or hexane, containing 1˜6carbons per molecule inside the reactor (S310), producing a mold byperforming reaction under a predetermined condition (S320), andperforming a thermal treatment on the mold (S330).

Here, the three-dimensional preform is produced by weaving carbon rodshaving the diameter of 1˜2 mm which have been prepared by a drawnmolding process, and it is manufactured and marketed by companies suchas ASNC (American Structure Needing Co.) in U.S.

Moreover, thermal gradient heating process S300 and reaction gasinfiltration process S310 can be referred to as thermal gradientchemical vapor infiltration. As for the thermal gradient chemical vaporinfiltration, it is performed on reaction material under the conditionwhere in the thermal gradient is created between the inside and outsideof the preform by providing a heating element in the middle of thecarbon fiber preform that is mounted inside the reactor and heating bythis heating element to create thermal conduction toward the outsidefrom the middle of the preform.

According to this method of thermal gradient chemical vaporinfiltration, density as well as thermal conductivity thereof increasesin the middle of the preform by causing thermal decomposition of gas forvapor infiltration in the middle of the preform where the reactiontemperature is arrived at relatively sooner. As a result, due to thethermal conductivity, infiltration is finally performed on the surfaceof the preform while the gas reaction area moves toward the surface byexpanding the range of the reaction temperature gradually toward thesurface from the middle.

Furthermore, mold producing process S320 is performed under heat risingrate of 10˜20° C./min, reaction temperature of 700˜1200° C., reactiongas concentration of 10˜100%, and reaction pressure of 250˜1,500 mbar;moreover, thermal treatment process S330 is performed at the maximumtemperature for 3˜5 hours under second thermal processing temperature of1,700˜2,500° C., vacuum level of 3˜5 mmHg, and heat rising rate of20˜100° C./hr.

Hereinafter, the clutch facing formed with carbon composition accordingto the present invention and the clutch facing formed with conventionalmethods will be compared. In the following graphs, the results are shownby testing twice the clutches which are installed respectively with eachtype of clutch facing.

FIG. 6 is a graph showing the test result wherein the clutch installedwith an organic-based facing is provided on chassis power testingmachine. The horsepower (left side) and torque (right side) are plottedaccording to the RPM (axis of abscissa). As shown in the drawing, it isseen that this clutch is soft at the starting time but slippery movementoccurs at abrupt acceleration or 2,800˜3,800 RPM, thereby decreasing theefficiency of power transmission from the driving shaft flywheel to gearshaft by 20˜30%.

FIG. 7 is a horsepower-torque graph of the clutch wherein a conventionalcopper-ceramic sinter facing is provided with. The output responsecharacteristic is good at abrupt acceleration, but it has a disadvantagethat soft start can not be attainable for automobiles, so drivers feeltired easily due to abrupt friction shock that occurs at the startingtime of 2,100˜2,700 RPM.

FIG. 8 is a graph showing the result wherein the clutch installed with acarbon composition clutch facing according to the present invention istested for the maximum torque at 4,500˜6,000 RPM, and it is seen thattorque is 44.4 kg-M and horse power is 331.2 PS at 4,800 RPM. Theautomobile installed with a clutch having the clutch disk assemblyaccording to the present invention can start softly; besides, it is seenthat slippery does not occur at abrupt acceleration and powertransmission from driving shaft flywheel to gear shaft is excellent. Soit can be applied even at high torque values.

FIG. 9 is a graph showing the response characteristic of gear shift forthe clutch installed with a clutch disk assembly according to thepresent invention. It is seen that response characteristic is excellentsince power transmission is soft without having loss or shock of powertransmission as well as impact position while shifting to the secondlevel from the first level at the starting time.

The characteristic of each clutch facing will be described in TABLE 1.TABLE 1 Clutch Organic- Copper-Ceramic Carbon—Carbon Characteristicbased Sinter Composition Friction Coefficient 0.10˜0.30 0.25˜0.400.25˜0.45 Max. 175˜300 260˜400 350˜450 Temperature(° C.) Torque (kg-m)17˜28 32˜40 44.4 Horse Power (Ps) 200˜300 270˜300 331.2 Press Plate440˜480 1000 1000 Load (kgf)

As shown in TABLE 1, friction coefficient shows similar tendency forboth copper-ceramic sinter and carbon-carbon composition, andtemperature shows higher for carbon-carbon composition when compared tothe friction coefficient. Moreover, organic-based material was brokendue to frictional heat and abrasion at the press plate load of 1000 kgf.In other words, it is seen that the carbon composition friction materialused for clutch disk assembly shows a remarkably improved performanceagainst organic-based material, and a slightly superior performancecompared to copper-ceramic sinter material.

It should be understood that a person having ordinary skill in the artto which the invention pertains can modify some of the embodiments withregard to the clutch for transmission power and the method ofmanufacturing the friction substance for the clutch according to thepresent invention as mentioned above. However, if such modifiedembodiments include essential elements of the invention it should beregarded that they are all within technical scope of the invention;moreover, technical idea of the invention should not be restricted bythe elements illustrated in the embodiments.

As described above, the clutch disk assembly and the method ofmanufacturing the friction substance for clutch according to theinvention can improve assemblability and reduce weight by simplifyinginto a single part without using shock absorbing apparatus such as coilspring or the like on clutch disk assembly. In addition, the powertransmission of an engine can be improved, and also it has an effectthat an automobile can start softly and slippery does not occur even atabrupt acceleration by providing with carbon-carbon composition orcarbon-silicon carbide composition having excellent shock absorptionfunction.

1. A method of manufacturing the friction substance for a clutchcomprising the steps of: performing a first thermal treatment whereincarbon fiber is thermally treated for graphitization at a first thermalprocessing temperature; producing a prepreg wherein resin is sprayed oncarbon fiber fabrics for forming the prepreg; producing a preformwherein carbon fiber and resin are stacked on said prepreg for formingthe preform; producing a mold wherein the mold is formed by using apress on said preform; and performing a second thermal treatment whereinsaid mold is thermally treated at a second thermal processingtemperature.
 2. The method of manufacturing the friction substance forthe clutch of claim 1, further comprising the step of cutting saidthermally treated carbon fiber at the length of 200˜2,000 μm by usingfiber-cutting machine between the first thermal treatment process andthe prepreg producing process.
 3. The method of manufacturing thefriction substance for the clutch of claim 2, further comprising adensification process for densifying said mold at a predetermineddensity using a carbonization/impregnation process for pressurizing atthe carbonizing pressure of 50˜2,000 kg/cm² within the range of750˜1,400° C. for 35 hours between said mold producing process and saidsecond thermal treatment process.
 4. The method of manufacturing thefriction substance for the clutch of claim 3, wherein said predetermineddensity is 1.3˜1.6 g/cm³.
 5. The method of manufacturing the frictionsubstance for the clutch of claim 1, wherein said first thermalprocessing temperature is 2,000˜3,000° C. during the first thermaltreatment process.
 6. The method of manufacturing the friction substancefor the clutch of claim 1, said mold is composed of 20˜75 weight % ofcarbon fiber and 25˜80 weight % of said resin, and molded throughheating within the range of 200˜300° C. in a press.
 7. The method ofmanufacturing the friction substance for the clutch of claim 1, whereinsaid second thermal treatment process is performed at the maximumtemperature for 3˜5 hours under second thermal processing temperature of1,700˜2,500° C., vacuum level of 3˜5 mmHg, and heat rising rate of20˜100° C./hr.
 8. The method of manufacturing the friction substance forthe clutch of claim 1 further comprising the steps of: performing asilicon powder addition process for adding silicon powder to said moldafter said second thermal treatment process; and performing a vacuumheating process for increasing the temperature within the range of1,450° C.˜2,200° C. and maintaining it for 0.1˜5.0 hours under vacuumatmosphere.
 9. The method of manufacturing the friction substance forthe clutch of claim 8, wherein said silicon powder 0.2˜5.0 times heavierthan said mold in weight ratio is added during said silicon powderaddition process.
 10. The method of manufacturing the friction substancefor the clutch of claim 8, wherein said mold is composed of 3˜25 weight% of silicon, 10˜65 weight % of silicon carbide, and 10˜80 weight % ofcarbon after finishing the vacuum heating process.
 11. The method ofmanufacturing the friction substance for the clutch of claim 1, whereinsaid mold is used for any one of clutch facing, friction pad, and presspad on which friction is made in the clutch.
 12. The method ofmanufacturing the friction substance for the clutch comprising the stepsof: heating for creating thermal gradient between the inside and outsideof said preform by mounting a heating element on a three-dimensionalpreform; infiltrating reaction gas containing 1˜6 carbons per moleculeinside said reactor; producing a mold by performing reaction under apredetermined condition; and performing a thermal treatment on saidmold.
 13. The method of manufacturing the friction substance for theclutch of claim 12, wherein said predetermined condition is heat risingrate of 10˜20° C./min, reaction temperature of 700˜1200° C., reactiongas concentration of 10˜100%, and reaction pressure of 250˜1,500 mbar.14. The method of manufacturing the friction substance for the clutch ofclaim 12, wherein said thermal treatment process is performed at themaximum temperature for 3˜5 hours under second thermal processingtemperature of 1,700˜2,500° C., vacuum level of 3˜5 mmHg, and heatrising rate of 20˜100° C./hr.
 15. The method of manufacturing thefriction substance for the clutch of claim 12, wherein said mold is usedfor any one of clutch facing, friction pad, and press pad on whichfriction is made in the clutch.